The present invention relates to freeze sensors that function to detect potential fluid freezes in water pipes and wirelessly transmit a freeze alert signal.
The freezing of pipes in houses and other structures has historically proven to be a significant problem in cold climates. In most cases, pipes in attics, crawl spaces, and other poorly heated or un-heated areas or extremities of the structure will be subject to freezing when the water is left still during prolonged periods of cold.
The ability to detect freeze conditions before freeze onset is an important part of any system that seeks to actively prevent freeze damage. However, the optimal locations for sensing near-freezing temperatures or other freeze conditions are often in areas that would be impractical to reach with AC electrical power. Therefore, the freeze sensor should be self-powered, using a battery or other similar means. The optimal sensing location, such as in a crawl space or basement, may also be remote from areas where a user could easily monitor or avert freeze conditions. In many instances, freeze prevention consists of opening a faucet or a fixture to let water flow through the pipe or pipes in question. Therefore, the ability of the freeze sensor to wirelessly transmit a freeze threat signal to a remote location provides for more flexible placement of sensors and a more user-accessible freeze alert system.
In the past, three general methods of freeze alarms have tried to provide pipe-freeze warnings:
1. A self-contained freeze alarm consists of a battery, temperature sensor, and an audio alarm within one housing. Such a device is shown in U.S. Pat. No. 4,800,371 issued to Arsi in 1989. Since the sensing location is typically far from the heated living space of the building, the alarm may be difficult for a user to hear. If the alarm were made powerful enough to be easily heard, then the batteries powering the alarm would be quickly drained. Further, such an alarm cannot provide freeze condition signals to an automated freeze-prevention system.
2. A household thermostat, with integrated temperature sensor, sends a “low heat” message to a monitoring service if the sensed temperature drops below some threshold temperature. Because the thermostat is not located in the unheated areas of the building where water pipes are most likely to freeze, the sensed temperature at the thermostat gives an extremely inexact indication of freeze likelihood, resulting in either frequent false alarms or alarms issued too late to prevent water freezing.
3. A water-activated alarm that provides an alarm in the event of a water leak is shown in U.S. Pat. No. 5,655,561 issued to Wendel et al on Aug. 12, 1997. Such a device provides an alert too late, after freeze damage has already occurred.